After 10 years, this significant Team Fortress 2 bug has been fixed

One-line fix for character model syncing error went undetected for a decade.

This video shows the now-patched bug that caused character hitboxes to sometimes go significantly out of sync with character models in Team Fortress 2.

These days, we're all used to games getting important post-launch patches that fix bugs and change gameplay balance issues that were present in the initial release. Usually, though, it doesn't take an entire decade for a major bug to be noticed and fixed in a popular game. That is what seems to have happened this week in Team Fortress 2, though.

Over on Reddit, user sigsegv__ lays out how the game would often get confused when a player switched between certain sets of characters in the middle of a match. Apparently, after switching from the soldier/pyro/demo/engineer/medic/spy to the scout/heavy/sniper (or vice versa), the character hitbox (that polygonal mesh that determines what area can be hit by a bullet) would start moving significantly out of sync with the visual character model that opponents could see on the server. This video illustrates the problem pretty clearly, showing character and hitbox animations that are well out of step.

The problem itself stems from a pretty arcane bit of code having to do with the differing orders that "pose parameters" are stored for these sets of character classes. Once identified, the fix involved changing only a single line of code, though as sigsegv__ notes, "knowing which one line of code is missing, and where, is the difficult part, you might say."

Sigsegv__ says this significant bug has been in the game since its launch in 2007, and while we haven't been able to independently confirm that, it's not hard to find people who have complained about apparent hitbox problems in Team Fortress 2 for years now. It just goes to show that even a decade later, the process of perfecting a popular game is never done.

Latest Ars Video >

War Stories | Ultima Online: The virtual ecology

When creating Ultima Online, Richard Garriott had grand dreams. He and Starr Long planned on implementing a virtual ecology into their massively multiplayer online role-playing game. It was an ambitious system, one that would have cows that graze and predators that eat herbivores. However, once the game went live a small problem had arisen...

War Stories | Ultima Online: The virtual ecology

War Stories | Ultima Online: The virtual ecology

When creating Ultima Online, Richard Garriott had grand dreams. He and Starr Long planned on implementing a virtual ecology into their massively multiplayer online role-playing game. It was an ambitious system, one that would have cows that graze and predators that eat herbivores. However, once the game went live a small problem had arisen...

Kyle Orland
Kyle is the Senior Gaming Editor at Ars Technica, specializing in video game hardware and software. He has journalism and computer science degrees from University of Maryland. He is based in the Washington, DC area. Emailkyle.orland@arstechnica.com//Twitter@KyleOrl